Pictures: Arkansas Oil Spill Darkens Backyards, Driveways

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Pictures: Arkansas Oil Spill Darkens Backyards, Driveways

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Backyard Nightmare

Crude oil flowed down driveways and swamped grass lawns in Mayflower, Arkansas, after an oil pipeline ruptured Friday afternoon. At least 12,000 barrels of Canadian crude oil and water spilled into a housing development over the weekend, causing the evacuation of 22 homes in the Little Rock suburb. Here, spilled crude fills a drainage ditch near the evacuated homes.

ExxonMobil's Pegasus pipeline, which is more than six decades old, runs from Patoka, Illinois, to Nederland, Texas, and can transport up to 90,000 barrels of oil per day. The company said Monday it was still investigating the cause of the spill, which the U.S. Environmental Protection Agency classified as "major." Cleanup is ongoing.

Emergency crews worked over the weekend to clean up the Canadian heavy crude that spilled among suburban homes in Mayflower, Arkansas. ExxonMobil deployed vacuum trucks, storage tanks, and about 120 workers, the company said in a statement. Crews also set up oil-absorbing booms at nearby Lake Conway, but no oil had reached the lake as of Monday. Resident Warren Andrews told local media that he expected it to be at least six days before he could return to his home. "It's just a sad accident. I didn't even know the oil pipeline was there," he said.

Photograph by Jacob Slaton, Reuters

Gulf-Bound Flow of Crude

The oil that filled ditches and driveways in Mayflower, Arkansas is heavy crude from the tar sands of Alberta, Canada, that was being transported via pipeline to Texas. An ExxonMobil spokesperson said that the company would excavate around the area of the leak to determine the cause and make repairs but could not say when or how long it would take.

The spill provided new ammunition for opponents of the proposed Keystone XL pipeline, which would transport oil from the tar sands to U.S. refineries on the Gulf Coast. Rep. Ed Markey (D-Mass.) called the spill "a troubling reminder that oil companies still have not proven that they can safely transport Canadian tar sands oil across the United States without creating risks to our citizens and our environment." (See related interactive map: "Keystone XL: Mapping the Flow of Tar Sands Oil.")

Photograph by Jacob Slaton, Reuters

A Different Type of Oil

Emergency crew workers vacuum up spilled oil and water near Interstate 40 in Mayflower, Arkansas, Sunday, after the weekend spill forced the evacuation of 22 homes.

Canada is the largest supplier of oil to the United States, sending about two million barrels per day across the border. Oil from the Alberta tar sands is a sticky, thick substance known as dilbit, or diluted bitumen, and some worry that transporting this unconventional oil is riskier than moving conventional crude. As Anthony Swift of the Natural Resources Defense Council notes in a blog post, tar sands pipelines operate at higher temperatures and may be more likely to rupture because of external corrosion.

Swift also contends that spills of tar sands oil are more damaging and harder to clean up, citing a 2010 tar sands spill into the Kalamazoo River: "Almost a billion dollars has been spent on cleanup, and 38 miles of that river are still contaminated," Swift writes. (See related photos: "Satellite Views of Canada's Tar Sands Over Time.")

Photograph by Jacob Slaton, Reuters

A Spreading Debate

Vacuum trucks and emergency crews continue the attempt to suck up spilled oil after the leak in Arkansas, but the debate over how—and whether—to transport the new gushes of oil from the tar sands and the Bakken shale through the U.S. heartland will continue after the Mayflower spill is gone. Refineries in the Midwest, where the Pegasus pipeline begins, will run out of capacity to handle Canada's heavy crude within the next few years. Texas refineries, on the other hand, are well equipped to take on the supply, and the Keystone XL pipeline would transport more than 800,000 barrels per day into the United States. The pipeline awaits approval from the Obama administration. (See related story: "Keystone XL Pipeline Path Marks New Battle Line in Oklahoma.")

A National Academies of Science committee is studying whether oil from the tar sands poses a special threat to pipeline integrity during transport, and whether current federal pipeline regulations are adequate to prevent a spill like the one that happened Friday in Arkansas.